feat: initial TychoRouter skeleton

- remappings.txt is used for more elegant imports
- decided not to include all helper methods in skeleton - just main swap method. They are properly documented in the jira tasks.
- add filter-paths to slither to exclude submodules, otherwise we will get slither warnings about permit2 and open-zeppelin using different solidity versions:

```
	- Version constraint ^0.8.20 is used by:
		-^0.8.20 (lib/openzeppelin-contracts/contracts/access/AccessControl.sol#4)
		-^0.8.20 (lib/openzeppelin-contracts/contracts/access/IAccessControl.sol#4)
		-^0.8.20 (lib/openzeppelin-contracts/contracts/utils/Context.sol#4)
		-^0.8.20 (lib/openzeppelin-contracts/contracts/utils/introspection/ERC165.sol#4)
		-^0.8.20 (lib/openzeppelin-contracts/contracts/utils/introspection/IERC165.sol#4)
	- Version constraint ^0.8.0 is used by:
		-^0.8.0 (lib/permit2/src/interfaces/IAllowanceTransfer.sol#2)
		-^0.8.0 (lib/permit2/src/interfaces/IEIP712.sol#2)
	- Version constraint ^0.8.28 is used by:
```

foundry/remappings.txt

@@ -0,0 +1,3 @@
+@openzeppelin/=lib/openzeppelin-contracts/
+@permit2/=lib/permit2/
+@src/=src/

foundry/slither.config.json

@@ -0,0 +1,3 @@
+{
+    "filter_paths": "lib"
+}

foundry/src/TychoRouter.sol

@@ -1,6 +1,68 @@
 // SPDX-License-Identifier: UNLICENSED
 pragma solidity ^0.8.28;
 
-contract TychoRouter {
+import "@openzeppelin/contracts/access/AccessControl.sol";
-    constructor() {}
+import "@permit2/src/interfaces/IAllowanceTransfer.sol";
+
+contract TychoRouter is AccessControl {
+    IAllowanceTransfer public immutable permit2;
+
+    //keccak256("NAME_OF_ROLE") : save gas on deployment
+    bytes32 public constant EXECUTOR_SETTER_ROLE =
+        0x6a1dd52dcad5bd732e45b6af4e7344fa284e2d7d4b23b5b09cb55d36b0685c87;
+    bytes32 public constant FEE_SETTER_ROLE =
+        0xe6ad9a47fbda1dc18de1eb5eeb7d935e5e81b4748f3cfc61e233e64f88182060;
+    bytes32 public constant PAUSER_ROLE =
+        0x65d7a28e3265b37a6474929f336521b332c1681b933f6cb9f3376673440d862a;
+    bytes32 public constant FUND_RESCUER_ROLE =
+        0x912e45d663a6f4cc1d0491d8f046e06c616f40352565ea1cdb86a0e1aaefa41b;
+
+    constructor(address _permit2) {
+        permit2 = IAllowanceTransfer(_permit2);
+        _grantRole(DEFAULT_ADMIN_ROLE, msg.sender);
+    }
+
+    /**
+     * @dev We use the fallback function to allow flexibility on callback.
+     * This function will delegate call a verifier contract and should revert if the
+     *  caller is not a pool.
+     */
+    fallback() external {
+        // TODO execute generic callback
+    }
+
+    /**
+     * @dev Executes a swap graph supporting internal splits token amount
+     *  splits, checking that the user gets more than minUserAmount of buyToken.
+     */
+    function swap(
+        uint256 amountIn,
+        address tokenIn,
+        uint256 minUserAmount,
+        bool wrapEth,
+        bool unwrapEth,
+        uint256 nTokens,
+        bytes calldata swaps,
+        IAllowanceTransfer.PermitSingle calldata permitSingle,
+        bytes calldata signature
+    ) external returns (uint256 amountOut) {
+        amountOut = 0;
+        // TODO
+    }
+
+    /**
+     * @dev Allows granting roles to multiple accounts in a single call.
+     */
+    function batchGrantRole(bytes32 role, address[] memory accounts)
+        external
+        onlyRole(DEFAULT_ADMIN_ROLE)
+    {
+        // TODO
+    }
+
+    /**
+     * @dev Allows this contract to receive native token
+     */
+    // TODO Uncomment once withdraw method is implemented - or else Slither fails
+    //    receive() external payable {}
 }

foundry/test/TychoRouter.t.sol

@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.28;
+
+import {Test, console} from "forge-std/Test.sol";
+import {TychoRouter} from "@src/TychoRouter.sol";
+
+contract TychoRouterTest is Test {
+    TychoRouter public tychoRouter;
+
+    function setupTychoRouter() public {
+        address permit2Address =
+            address(0x000000000022D473030F116dDEE9F6B43aC78BA3);
+        tychoRouter = new TychoRouter(permit2Address);
+    }
+
+    function testSetupTychoRouter() public {
+        setupTychoRouter();
+    }
+}